The invention relates generally to the field of ultrasonic imaging, and in particular to the imaging of body lumens or cavities. More specifically, the invention relates to the use of imaging devices that are rotated at high speeds to produce an image of a body lumen or cavity.
The use of rotatable imaging devices to produce an image of a body lumen is well known. For example, one pioneering effort is described in U.S. Pat. No. 4,794,931, the complete disclosure of which is herein incorporated by reference. In U.S. Pat. No. 4,794,931, a drive cable having an imaging element at a distal end is rotated within a catheter to product an image of a diseased region prior to therapy.
Recently, there has been an advancement in the field of rotatable imaging devices where the size of the imaging devices has been substantially reduced. For instance, one such imaging device is described generally in copending U.S. application Ser. No. 09/017,578, filed Feb. 3, 1998, the complete disclosure of which is herein incorporated by reference. Such an imaging device is small enough to operate within traditional guide wire lumens of therapeutic catheters, such as angioplasty balloon catheters.
One potential problem that may arise when operating imaging devices within catheter lumens having a distal exit port, such as within guide wire lumens of therapeutic catheters, is that the rotating imaging device may accidentally be advanced beyond the distal exit port and into the body lumen, thereby posing a risk of damage to the luminal wall.
Hence, it would be desirable to provide a way to prevent the unwanted advancement of a rotating imaging device beyond a distal exit port of a catheter. Such a safeguard should be reliable and easy to use to maximize its acceptance in the industry.